Strain and kinematic vorticity analysis of the Louzidian low-angle ductile shear detachment zone in Chifeng, Inner Mongolia, China

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	Strain and kinematic vorticity analysis of the Louzidian low-angle ductile shear detachment zone in Chifeng, Inner Mongolia, China
	Li, JB (Li JianBo); Wang, T (Wang Tao); Ouyang, ZX (Ouyang ZhiXia)
刊名	SCIENCE CHINA-EARTH SCIENCES
	2010
卷号	53 期号:11 页码:1611-1624
关键词	Louzidian low-angle ductile shear detachment zone mylonite strain intensity kinematic vorticity principal stress
ISSN号	1674-7313
英文摘要	The Louzidian low-angle ductile shear detachment zone at the south of Chifeng is a SE-dipping, low-angle normal fault system. It is composed mainly of ductile shear zone, ductile-brittle shear zone and brittle fault zone. The ductile shear zone consists of, from bottom to top, mylonitic rocks, protomylonites and mylonites. Finite strain measurement of feldspar strain markers from those rocks using the R (f) /I center dot method shows that strain intensities (Es) of the mylonite at core of the ductile shear zone (Es=0.65-0.96) are higher than those of the mylonitic rocks close to the granite intrusions (Es=0.59-0.62) and of the protomylonites at top of the ductile shear zone (Es= 0.47-0.70), and the strain types of the protomylonites and mylonties are elongate strain and plane-flattening strain, respectively. The kinematic vorticity values (W (k) ) estimated by the Polar Mohr diagram and the Rigid Grain Net range from 0.81 to 0.90 with an average of 0.85 for the protomylonites, and from 0.53 to 0.80 with 0.66 on average for the mylonites; Wk values of the extensional crenulation cleavage, i.e., C', estimated by C' method range from 0.63 to 0.37 with an average of 0.50. The angles between the maximum principal stress and shearing direction determined using the Maximum effective moment criterion evolved from 61A degrees to 69A degrees and to 75A degrees, and finally normal to shearing direction. The results of strain and kinematic vorticity measurements suggest that high strain corresponds to low kinematic vorticity. Kinematic vorticity measurements show that the Louzidian low-angle ductile shear detachment zone is a result of a combination of simpledominated general shearing at the early stage and pure-dominated general shearing at the late stage. All these, together with isotope geochronology and regional tectonic background, suggest that the Louzidian ductile shear detachment zone resulted from a combination of crust extension and magma intrusion. The model of simple shear at the early stage and pure shear at the late stage in the formation of metamorphic core complex has probably general significance.
学科主题	构造地质学
WOS关键词	METAMORPHIC CORE COMPLEX ; SOUTHERN CHIFENG ; NORTHERN CHINA ; NORMAL FAULTS ; DEFORMATION ; EXTENSION ; FLOW ; MECHANISM ; EVOLUTION ; BASINS
WOS研究方向	Geology
语种	英语
出版者	SCIENCE PRESS
WOS记录号	WOS:000284167800005
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39193]
专题	中国地质调查局
作者单位	E China Inst Technol, Fuzhou 344000, Peoples R China
推荐引用方式 GB/T 7714	Li, JB ,Wang, T ,Ouyang, ZX . Strain and kinematic vorticity analysis of the Louzidian low-angle ductile shear detachment zone in Chifeng, Inner Mongolia, China[J]. SCIENCE CHINA-EARTH SCIENCES,2010,53(11):1611-1624.
APA	Li, JB ,Wang, T ,&Ouyang, ZX .(2010).Strain and kinematic vorticity analysis of the Louzidian low-angle ductile shear detachment zone in Chifeng, Inner Mongolia, China.SCIENCE CHINA-EARTH SCIENCES,53(11),1611-1624.
MLA	Li, JB ,et al."Strain and kinematic vorticity analysis of the Louzidian low-angle ductile shear detachment zone in Chifeng, Inner Mongolia, China".SCIENCE CHINA-EARTH SCIENCES 53.11(2010):1611-1624.